I don't know if this is a model that will stand up to some rigorous
learning/experience-building or not (and any opinions on that would be
wonderful!) I also don't know if this website is reliable or reputable,
because I've never heard of anyone buying one from here.

ALSO: Does a 300mm seat post vs. a 400mm seat post make a huge
difference when you're learning? I'm 5'5", and it sounds like I should
get a 300mm, but some models only come in 400mm, and one person told me
that seat post doesn't really matter. I'm confused.

that's not a bad price for a torker, as far as I have seen, and the FREE
SHIPPING is going to save you some money. I don't know if the website is
reputable, and I don't know about the other unis you like, but torkers
seem to be great first unis. They will be very strong, though not well
suited to much MUni or Trials, because you cannot fit a good MUni tire
into the torker frame, othewise they would be exceptionally good.
However, mos everything you mentioned will stand up fine to learning,
though the viscount saddle has been known to fall apart. A bonus on the
torker is that it comes with a Miyata style saddle, which is comfortable
and has a handle which will help a lot for once you have learned to ride
and want to learn to hop.

Seat Posts- The seat post length won't matter unless it's too short,
because you can easily cut it down until it fits.

The semcycle is a good uni, but the seat is not quite as good as the
torker, though the hub is quite strong and good.

I don't know about the schwinn, but its seat is also not as good.

I like the Nimbus II, because it has a Kris Holm saddle, which is better
than the torker, and has a very nice tire. However, I think the torker
might be stronger, though I'm not sure.

--
Fuego - Ride to Ruin, and a Red Dawn!

"Unicycling is more about the center of concentration than the center of
balance."

I just wish I knew some people who had ordered things from that
website.... And, yeah, the free shipping is awesome, considering that
the shipping would probably bump me back up to the price of the rest of
the unis i listed.

The most reputable web site out there is still Unicycle.com. Darren
Bedford is also great for orders in Canada, but his is mostly over the
phone business, as the web site is still struggling to be e-commerce.

Sunrise Cyclery is a bike shop in Massapequa Park, Long Island. I drove
by there many times during my 10 years living in the area, but don't
know if I ever went in there. It is obvious by their web site that they
are a hard-working store who want to do a good job. They also advertise
on Google, so they want to get their name out there and not just be a
local shop. That's great. But they are still, at the core, a bike shop.
Somebody there obviously is interested in unicycles, but they are mainly
a reseller.

Unicycle.com is the source (their name was originally
"unicyclesource.com"). The business was built from the ground up to be
all about unicycles. They are not a bike shop. They have the most
complete selection of parts and products online, and will work hard to
make sure you are a satisfied customer. If I need something, I will
always go to Unicycle.com first, to support them, then to other sources
if Uni.com doesn't have what I need.